qmVEBSITY  OF   CALIFORKIA   PUBLICATIONS 

COLLEGE  OF  AGRICULTURE 

AGRICULTURAL  EXPERIMENT  STATION 

BERKELEY.  CALIFORNIA 


DUST  AND  THE  TRACTOR  ENGINE 


BY 

A.  H.  HOFFMAN 


BULLETIN  No.  362 

May,  1923 


UNIVERSITY  OF  CALIFORNIA  PRESS 

BERKELEY,  CALIFORNIA 

1923 


David  P.  Barrows,  President  of  the  University. 

EXPERIMENT  STATION  STAFF 

HEADS   OF  DIVISIONS 

Thomas  Forsyth  Hunt,  Dean. 

Edward  J.  Wickson,  Horticulture  (Emeritus). 

,  Director  of  Resident  Instruction. 

C.  M.  Haring,  Veterinary  Science,  Director  of  Agricultural  Experiment  Station. 

B.  H.  Crocheron,  Director  of  Agricultural  Extension. 

C.  B.  Hutchison,  Plant  Breeding,  Director  of  the  Branch  of  the  College  of 

Agriculture  at  Davis. 
H.  J.  Webber,  Sub-tropical  Horticulture,  Director  of  Citrus  Experiment  Station. 
William  A.  Setchell,  Botany. 
Myer  E.  Jaffa,  Nutrition. 
Ralph  E.  Smith,  Plant  Pathology. 
John  W.  Gilmore,  Agronomy. 
Charles  F.  Shaw,  Soil  Technology. 
John  W.  Gregg,  Landscape  Gardening  and  Floriculture. 
Frederic  T.  Bioletti,  Viticulture  and  Fruit  Products. 
Warren  T.  Clarke,  Agricultural  Extension. 
Ernest  B.  Babcock,  Genetics. 
Gorpon  H.  True,  Animal  Husbandry. 
Walter  Mulford,  Forestry. 
James  T.  Barrett,  Plant  Pathology. 
W.  P.  Kelley,  Agricultural  Chemistry. 
H.  J.  Quayle,  Entomology. 
Elwood  Mead,  Rural  Institutions. 
H.  S.  Reed,  Plant  Physiology. 
L.  D.  Batchelor,  Orchard  Management. 
W.  L.  Howard,  Pomology. 
IFrank  Adams,  Irrigation  Investigations. 

C.  L.  Roadhouse,  Dairy  Industry. 
R.  L.  Adams,  Farm  Management. 

W.  B.  Herms,  Entomology  and  Parasitology. 
John  E.  Dougherty,  Poultry  Husbandry. 

D.  R.  Hoagland,  Plant  Nutrition. 
G.  H.  Hart,  Veterinary  Science. 

L.  J.  Fletcher,  Agricultural  Engineering. 
Edwin  C.  Voorhies,  Assistant  to  the  Dean. 

.  DIVISION  OF  AGRICULTURAL  ENGINEERING 

L.  J.  Fletcher  James  Koeber 

A.  H.  Hoffman  E.  G.  McKibben 

B.  D.  Moses  J.  D.  Long 
R.  R.  Thomson  W.  L.  Zink 

H.    L.   B ELTON 


t  In  cooperation  with  Office  of  Public  Roads  and  Rural  Engineering,  U.  S.  Department  of 
Agriculture. 


DUST  AND  THE   TRACTOR   ENGINE1 

By  A.  H.  HOFFMAN 


CONTENTS  Page 

Dust  Causes  Rapid  Wear 470 

Efficiency  of  Air  Cleaners 470 

Air  Cleaners  Not  All  Equally  Efficient 470 

Tests  Made  at  Davis 470 

The  No.  1  Standard  Dust 471 

How  the  Dust  Was  Fed  to  the  Cleaners 471 

Finding  the  Efficiency  of  the  Cleaner 471 

Three  Standard  Efficiency  Tests 471 

Special  Tests 472 

Low  Water  Level  Test 472 

Fill-up  Test 472 

Vacuum  Tests 472 

Power  Tests 472 

The  Cleaners  Tested 474 

Source 474 

Classification 474 

Water  Type 474 

Dry  Type 474 

Oil  Type 474 

A  Homemade  Cleaner 476 

Identification  Table 476 

Results  of  the  Tests 476 

Tables:   Identification  of  Cleansers  Tested.    Table  1 477 

General  Summary.   Table  2 478 

FiU-up  Tests.   Table  3 479 

Chaff  Tests.   Table  4 480 

Notes  Taken  from  the  Test  Records 480 

Graphs 482 

Dust-Separation  Efficiency.   Fig.  6 482 

Vacuum  or  Choking  Effect.   Fig.  7 483 

Effect  on  Power  of  Engine.   Fig.  8 485 

Vacuum  Effect  Not  Entirely  Harmless 482 

How  to  Get  Best  Results  from  Air  Cleaners 484 

No  Leaky  Connections 484 

Breather  Pipe  Should  Have  Clean  Air 484 

Keep  Water  Level  High 484 

Place  Air  Intake  High 484 

Give  Needed  Attention 485 

A  Simple  Efficiency  Test  for  Air  Cleaners 486 

Acknowledgments 486 

1  No  attempt  is  made  in  this  paper  to  illustrate  or  to  explain  apparatus  and 
methods  for  testing  air  cleaners.  For  complete  description  see  Hoffman,  A.  H., 
' '  Efficiency  of  Dust  Separation  in  Air  Cleaners  for  Internal  Combustion  Engines, ' ' 
Transactions  A.  S.  A.  E.,  vol.  16  (1922).  Reprints  in  limited  numbers  may  be 
had  by  addressing  Agricultural  Engineering  Division,  University  of  California, 
Davis,  Calif.     Full  data  of  all  tests  are  on  file  and  accessible  at  the  same  place. 


470  UNIVERSITY    OF    CALIFORNIA — EXPERIMENT    STATION 

Dust  causes  rapid  wear. — When  it  is  remembered  that  fifty-five 
per  cent  of  the  average  dust  floating  around  in  California  fields 
(fig.  1)  is  shown  by  test  to  be  sand,  it  will  not  be  hard  to  understand 
why  a  tractor  engine  needs  an  efficient  air  cleaner.  An  engineer  of 
a  prominent  California  tractor  manufacturing  company  recently 
stated  that  their  latest  model  tractor  would  run  in  dusty  conditions 
under  full  load  for  three  thousand  hours  with  no  adjustments  what- 
ever, and  for  six  thousand  hours  with  only  minor  adjustments,  pro- 
vided it  had  a  satisfactory  air  cleaner;  but  that  without  an  air  cleaner 
the  engine  would  be  ruined  in  fifteen  hours'  use. 


Fig.  1. — Typical  conditions  under  which  the  tractor  in  California  must  do  its 
work.  Dust  entering  by  way  of  carburetor  and  breather  pipe  mingles  with  the 
lubricating  oil  and  makes  a  grinding  mixture  which  quickly  wears  out  many  parts 
of  the  engine. 

EFFICIENCY   OF   AIR   CLEANERS 

Air  cleaners  not  all  equally  efficient. — It  has  long  been  known  that 
the  numerous  makes  and  types  of  air  cleaners  on  the  market  differ  in 
their  ability  to  remove  dust  from  the  entering  air,  in  the  degree  to 
which  their  use  imposes  vacuum  or  choking  on  the  carburetor  intake, 
and  in  their  effect  on  the  maximum  possible  power  to  be  obtained  from 
the  engine ;  yet  there  has  been  no  publication  of  authoritative  tests 
previous  to  those  here  given  by  which  the  user  might  know  what 
service  he  might  reasonably  expect  from  any  given  air  cleaner. 

Tests  made  at  Davis. — To  determine  their  dust-separation  efficiency, 
vacuum  imposition  and  effect  on  power,  a  long  series  of  tests  was  made 
at  the  Branch  of  the  College  of  Agriculture,  Davis,  Calif.  Twenty- 
six  cleaners  (described  later)  were  tested.  A  twenty-five  h.p.  four- 
cylinder  engine  was  used  on  which  to  make  the  tests  in  order  to  have 


Bulletin   362]  DUST  AND   THE   TRACTOR  ENGINE  471 

conditions  as  nearly  as  possible  like  those  encountered  in  actual  work. 
Since  in  a  field  test  it  would  be  very  difficult  to  avoid  errors  due  to 
differences  in  kind  of  soil,  dryness  of  soil,  direction  and  strength  of  the 
wind,  temperature  and  moistness  of  the  air,  etc.,  it  was  deemed  better 
to  make  the  tests  in  the  laboratory  where  both  load  and  speed  could 
be  made  the  same  for  all  cleaners  tested,  and  where  a  standard  dust 
might  be  fed  to  all  cleaners  in  the  same  manner,  in  the  same  amounts, 
and  at  the  same  rates. 

The  No.  1  standard  dust  used  in  the  efficiency  tests  was  made  up 
from  fifty-pound  soil  samples  taken  from  ten  cultivated  fields  or 
orchards  scattered  throughout  the  principal  tractor-using  areas  of 
this  state.  The  ten  soils  were  dried  and  pulverized  and  the  finest 
parts  taken  out  by  an  air-floating  process.  The  dusts  so  obtained 
were  mixed  to  make  the  No.  1  standard  dust ;  hence  it  is  a  composite 
which  may  be  regarded  as  fairly  representing  the  average  dust  in 
our  fields  at  a  height  of  about  four  feet  above  ground. 

How  the  dust  was  fed  to  the  cleaners. — The  standard  quantity  of 
dust  fed  in  was  fifty  grams  (1.76  ounces),  and  the  usual  standard 
time  was  about  thirty  minutes.  The  dust  was  fed  to  the  cleaner  under 
test  by  placing  it  in  a  tin  tube  from  which  a  plunger  pushed  it  out 
slowly  against  a  revolving  bristle  brush  wheel  by  which  it  was  swept 
in  a  very  fine  cloud  directly  into  the  air  stream  entering  the  cleaner. 

Finding  the  efficiency  of  the  cleaner. — The  air  leaving  the  cleaner 
passed  next  through  an  'absolute  cleaner'  which  caught  the  dust  not 
caught  by  the  cleaner  under  test,  and  then  into  the  tractor  engine.  The 
cloths  of  the  absolute  cleaner  were  thoroughly  dried  and  accurately 
weighed  before  and  after  the  test,  the  difference  in  weight  being  the 
weight  of  dry  dust  not  caught  by  the  cleaner  under  test.  Where  this 
weight  was  five  grams  the  efficiency  would  be  90  per  cent. 

Three  standard  efficiency  tests. — Three  standard  tests  were  run 
on  each  cleaner  as  follows : 

1.  A  test  at  normal  speed  (1200  r.p.m.),  normal  load  (20.4  h.p.), 

and  quick  dust  feed  (50  grams  in  30  minutes). 

2.  A  test  at  normal  speed,  light  load  (12.6  h.p.),  and  quick  dust 

feed. 

3.  A  service  test,  at  quick  dust  feed,  in  which  working  conditions 

were  approximated.  In  this  run,  variable  load,  variable 
speed,  idling,  backfiring  and  quick  pick-up  with  wide  open 
throttle,  were  features.  At  intervals  load  and  speed  were 
brought  to  normal  and  readings  of  vacuum  were  taken.  (See 
table  2,  p.  478,  and  fig.  6.) 


472  UNIVERSITY    OF    CALIFORNIA — EXPERIMENT    STATION 

Special  tests  were  run  when  circumstances  required.  Among  these 
were  a  low  water  level  test,  a  fill-up  test,  and  a  chaff  test.  On  water 
type  cleaners  (also  on  one  oil  type  cleaner)  where  the  level  of  the 
liquid  would  be  lowered  by  use,  an  efficiency  test  was  run  with  the 
liquid  at  the  low  level  mark  (if  any).  On  cleaners  which  from  their 
construction  might  presumably  have  their  efficiency  or  vacuum 
affected  by  the  entering  dust  a  so-called  fill-up  test  was  run.  This 
was  not  a  standard  efficiency  test  and  for  it  the  material  fed  in  was 
a  prepared  dust  known  as  No.  2  standard.  It  was  uniform,  but  was 
much  coarser  and  denser  than  the  No.  1  standard.  The  purpose  of 
the  fill-up  tests  was  to  obtain  a  rough  estimate  of  what  might  be 
expected  of  the  cleaner  when  neglected  and  subjected  to  gross  abuse. 
The  amount  of  dust  fed  in  fill-up  tests  was  as  much  as  seven  pounds 
in  some  cases.  The  rate  of  feeding  was  also  very  rapid  and  for  this 
reason  little  importance  is  to  be  given  to  those  instances  in  the  fill-up 
test  where  the  cleaner  did  not  show  up  well.  However,  where  a 
cleaner  under  this  very  severe  test  was  able  to  maintain  good  efficiency 
and  low  vacuum,  its  ability  to  stand  abuse  would  in  a  measure  seem 
to  be  established.     (See  table  3,  p.  479.) 

The  chaff  test  was  designed  for  cleaners  not  provided  with  an 
adequate  screen  and  of  such  interior  construction  as  presumably  to 
have  the  vacuum  affected  by  the  entrance  of  insects,  leaves,  and  other 
organic  refuse.  Ten  grams  of  dry  wheat  chaff  passed  through  one- 
fourth  inch  mesh  screen  was  allowed  to  be  drawn  into  the  air  stream 
entering  the  cleaner,  and  the  effect  on  the  vacuum  due  to  the  cleaner 
was  noted.     (See  table  4,  p.  480.) 

Vacuum  tests. — The  vacuum  or  choking  effect  was  measured  by  use 
of  a  U-tube  manometer  at  intervals  during  the  efficiency  test  runs 
and  also  during  tests  made  to  find  the  effect  of  the  cleaners  on  the 
power  of  the  engine.     (See  table  2  and  figs.  7  and  8.) 

Power  tests. — The  tests  to  find  effect  on  power  were  run  as  follows. 
After  warming  up  thoroughly,  the  engine  was  run,  cleaner  off,  with 
wide  open  throttle  and  carburetor  adjusted  for  highest  power.  Next 
came  a  similar  run  with  cleaner  on,  the  carburetor  being  readjusted; 
then  immediately  another  run  with  cleaner  off.  The  highest  power  at 
standard  speed  obtained  in  the  run  with  cleaner  on  was  divided 
by  the  average  of  the  highest  powers  obtained  at  standard  speed  in 
the  first  and  third  runs.  The  per  cent  so  obtained  was  used  as  the 
means  of  comparing  the  power  effects  of  the  several  cleaners.  (See 
table  2,  p.  478,  and  fig.  8.) 


Bulletin  362] 


DUST   AND   THE   TRACTOR   ENGINE 


473 


Fig.  2. — Water  type  cleaners. 

1.  J.  I,  Case  Threshing  Machine  Company. 

2.  Cleveland  Tractor  Company.     (Cletrac  W.) 
8.  W.  H.  L.  Donaldson. 

10.  Ford  Motor  Company  (Fordson). 

11.  International  Harvester  Company.      (10-20  Titan.) 

14.  Eoss-Wortham  Company.     (E.  W.) 

15.  Stewart-Warner  Speedometer  Corporation. 

16.  Tractor  Appliance  Company.     (Taco  Siphon.) 
24.  Samson  Tractor  Company.     (Model  M.) 


474 


UNIVERSITY    OF    CALIFORNIA EXPERIMENT    STATION 


THE    CLEANERS    TESTED 

Source. — The  manufacturer  of  each  of  the  thirty2  cleaners  tested 
was  invited  to  determine  the  size  of  cleaner  to  fit  the  engine  on  which 
the  tests  were  to  be  run  and  to  choose  the  particular  cleaner  to  be 
tested.  With  a  single  exception  manufacturers  availed  themselves  of 
this  privilege. 

Classification. — For  purposes  of  comparison  the  cleaners  were 
classified  into  three  groups  according  to  their  mode  of  operation,  as 
water  type,  dry  type,  and  oil  type. 


Fig.  3. — Dry  type  cleaners. 

•  6.  Donaldson  Company,  Inc.      (45  h.p.  tractor.) 

7.  Donaldson  Company,  Inc. 
13.  Liljegren  and  Dugain,  "Success"    (for  Fordson). 

17.  Copied  from  eiderdown  cleaner  shown  in  Chilton  Tractor  Jour- 

nal, June  1,  1919,  p.  41. 

18.  United  Manufacturing  and  Distributing  Company.      (Collector 

type.) 

19.  United  Manufacturing  and  Distributing  Company.      (Ejector 

type.) 

23.  Bennett  Carburetor  Company. 

25.  Stromberg  Motor  Devices  Company. 

Of  the  eleven  water  type  cleaners  tested,  seven  (nos.  1,  2,  10,  11, 
14,  24,  and  24a)2  passed  the  dusty  air  under  the  edges  of  a  float,  two 
(8  and  27  )2  used  the  centrifugal  principle,  and  two  (15  and  16)  used 
the  atomizer  principle. 


2  Twenty -six  cleaners  were  received  in  time  for  all  the  tests,  four  (nos.  24  a,  25  a, 
25b,  and  27)  in  time  for  power  tests  only.     See  tables  nos.  1  and  2. 


Bulletin  362] 


DUST   AND   THE    TRACTOR   ENGINE 


475 


Of  the  ten  dry  type  cleaners,  two  (13  and  17)  used  cloth  niters, 
the  other  eight  employed  the  centrifugal  principle,  the  whirl  being 
obtained  by  means  of  vanes,  tangentially  placed  inlets,  or  both  (6,  7, 
23,  25,  25a3  and  25b3),  or  by  a  rotating  member  (18  and  19).  Some 
of  these  (25,  25a,  and  25b)  had  an  ejector  operated  by  exhaust  gas 
from  the  engine  to  throw  the  separated  dust  to  the  outside  air,  while 
another  (19)  ejected  the  dust  by  the  centrifugal  action  of  the  rotating 
member.    These  last  cleaners  therefore  did  not  require  to  be  emptied. 


Fig.  4. — Oil  Type  Cleaners. 


3.  Dailey  Bros. 

4.  Dailey  Bros. 

5.  Donaldson  Co.,  Inc. 
9.  Fageol  Motors  Co. 

12.  A.  E.  Palmer  (Experimental; . 


20.  Vortox  Mfg.  Co.  (Pomona). 

21.  Vortox  Mfg.  Co.  (Pomona). 

22.  Vortox  Mfg.  Co.  (Pomona). 
26.  Dailey  Bros.  (Model  1). 


Of  the  nine  oil  type  cleaners,  one  (12)  employed  the  atomizer 
principle;  the  other  eight  had  oiled  niters,  one  (9)  of  cloth,  three 
(3,  4,  26)  of  fibrous  material,  tAvo  (21  and  22)  of  fibrous  material 
combined  with  oil  centrifugal,  one  (20)  of  wire  combined  with  oil 
centrifugal,  and  one  (5)  of  fibrous  material  combined  with  dry 
centrifugal. 


s  For  24a,  25a,  25b,  and  27  see  tables  nos.  1  and  2. 


476 


UNIVERSITY    OF    CALIFORNIA EXPERIMENT    STATION 


A  homemade  cleaner. — One  cleaner,  no.  17  (called  no.  17'  when 
outer  shell  is  left  off,  as  in  fig.  5)  was  made  up  by  a  local  tinsmith. 
It  is  pictured  in  the  Chilton  Tractor  Journal,  June  1,  1919,  as  an 
example  of  an  obsolete  type.  Made  up  as  shown  and  with  two  thick- 
nesses of  eiderdown  blanketing  wrapped  on,  nap  side  out,  over  the 
cylinder  of  one-half  inch  mesh  hardware  cloth,  its  performance  under 
all  tests  was  very  satisfactory.  A  cover  is  not  essential  to  its  oper- 
ation.   It  may  be  placed  in  any  position. 


Fig.  5. — A  homemade  cleaner. 

Eiderdown  cleaner  (no.  17  and  17')  cover  removed,  cloth  laid  back.  A 
(9"  X  18")  cylinder  of  wire  screen  soldered  to  heavy  tin  pans.  Tube  (size  of 
carburetor  inlet)  extending  to  inside.  Iron  bars  suitable  for  attachment  to  tractor 
riveted  to  ends.     Two  thicknesses  of  eiderdown  blanketing,  nap  side  out,  tied  on. 


Identification  table. — The  cleaners  tested  are  listed  in  table  1,  the 
essential  dimensions  by  which  they  may  be  identified  and  compared 
being  given.  A  list  of  air  cleaner  manufacturers'  addresses  may  be 
obtained  from  the  Division  of  Agricultural  Extension,  University  of 
California,  Berkeley,  or  from  the  Division  of  Agricultural  Engineer- 
ing, University  Farm,  Davis,  California. 

The  results  of  the  tests. — Table  2  gives  a  general  summary  of  the 
tests.    Table  3  summarizes  the  fill-up  tests,  and  table  4  the  chaff  tests. 


Bulletin  362] 


DUST  AND   THE   TRACTOR   ENGINE 


477 


TABLE  1 

Identification  of  Cleaners  Tested 


Make 

or 
name 

Type 

Weights 

Outlet 
Diam. 
inside, 
inches 

Inlets 

Size  of  body 

No. 

Clean 
dry 
lbs. 

Ready 

for  use, 

lbs. 

No. 

Diam.  inches 
or  size  of 
opening 

proper, 

Height,  Length, 

Width,  inches 

1 

Case 

Wet 

18-3/4 

39-1/4 

2-1/2 

1 

2-1/2 

19-1/2  x  12D 

2 

Cletrac  W 

Wet 

57-1/4 

74-1/2 

1-1/2 

1 

1-1/2 

14  x  13  x  9 

3 

Dailey 

Oil 

11-3/4 

12 

1-3/4 

1 

1-7/8 

18  x  7-1/2D 

4 

Dailey 

Oil 

12 

12-1/4 

1-7/8 

1 

1-7/8 

18  x  10D 

5 

Donaldson 

Oil& 

Dry 

5-3/4 

5-3/4 

1-1/2 

15 

1 -1/4  x  3/8 

16  x8D 

6 

Donaldson 

Dry 

5-1/4 

5-1/4 

2-1/4 

1 

2-1/4 

12  x  11D 

7 

Donaldson 

Dry 

2 

2 

2 

15 

1  x  1/4 

11-1/4  x  8D 

8 

Donaldson 

Wet 

15 

10 

1-7/8 

1 

1-3/4 

17x9D 

9 

Fageol 

Oil 

9-1/4 

9-1/2 

1-1/2 

1 

1-1/2 

13-1/2  x  10-3/4D 

10 

Fordson 

Wet 

40-1/4 

53-1/4 

1-3/4 

1 

1-1/2  x  1-1/2 

12  x  14-1/2  x  6 

11 

I.H.C. 

Wet 

18 

34 

2 

1 

2-1/2 

18-1/2  x  10-1/2D 

12 

Palmer 

Oil 

9-1/2 

15 

1-11/6 

1 

1  x  3 

18  x  8-1/2D 

13 

Success 

Dry 

10-1/2 

10-1/2 

1-7/8 

1 

1-7/8 

15  x8D 

14 

R.W. 

Wet 

8-3/4 

18-1/2 

1-3/8 

6 

1 

15  x9D 

15 

Stewart- 
Warner 

Wet 

7 

16-1/4 

1-3/8 

2 

1-3/4  x  2 

13  x  9D  x  6-1/2 

16 

Taco 
Siphon 

Wet 

44-1/2 

56 

2 

1 

2-1/2 

12-1/2  x  16  x  7-1/2 

17 

Eiderdown 
(closed) 

Dry 

9 

9 

1-7/16 

1 

2 

26  x  12-1/2D 

17' 

Eiderdown 
(open) 

Dry 

5 

5 

1-7/16 

1 

565  sq.  in. 

19  x  10D 

18 

United 
collector 

Dry 

8-3/4 

8-3/4 

1-1/2 

1 

1-1/2 

10-1/2  x  5D 

19 

United 
ejector 

Dry 

2-1/2 

2-1/2 

1-7/16 

1 

3-1/4 

7x5D 

20 

Pomona 

Oil 

4 

5-3/4 

2 

1 

2 

13-1/2  x  4-5/8D 

21 

Pomona 

Oil 

3-1/4 

5 

2 

1 

2 

13  x  4-5/8D 

22 

Pomona 

Oil 

9 

16-1/2 

2 

1 

2-1/2 

15  x  10D 

23 

Bennett 

Dry 

4-1/8 

4-1/8 

1-3/4 

3 

1-3/16 

9  x6D 

24 

Samson 

Wet 

27-1/4 

42-1/2 

1-3/8 

1 

1-3/8 

14  x  12-1/2  x  7 

24a 

Samson 

Wet 

28-1/4 

37-1/4 

1-1/4 

1 

2  x  6-1/2 

15  x  10D 

25 

Stromberg 

Dry 

3-1/2 

3-1/2 

1-5/8 

12 

7/8  x  3/8 

14x6D 

25a 

Stromberg 

Dry 

3-1/2 

3-1/2 

1-5/8 

12 

7/8  x  3/8 

14  x  6D 

25b 

Stromberg 

Dry 

4-3/4 

4-3/4 

1-3/4 

12 

1-1/8  x  3/8 

16  x  7-1/2D 

26 

Dailey 

Oil 

10 

10-1/2 

1-9/16 

1 

1-1/2 

17-1/2  x  10D 

27 

Bennett 

Wet 

8-1/4 

15-1/4 

1-3/4 

1 

1-3/4 

12x9D 

478 


UNIVERSITY    OF    CALIFORNIA— EXPERIMENT    STATION 


TABLE  2 

Summary  of  Tests 


Make  or 
trade 
name 

Dust  separating  efficiency 
per  cent 

Vacuum 

Maxi- 
mum 

power 
with 

cleaner 
on 

No. 

At  20.4  h.p. 
1200  R.P.M. 
inches  water 

At  max- 
imum 
h.p.  and 

1200 
R.P.M. 
inches 
water 
Cleaner 
cleaned 
out 
after 
effi- 
ciency 
tests 

Ratio 

h.p. 

with 

cleaner 

on  to 

Average 

all 

tests 

Service 
run 

Low 
Water 
or  oil 

Cleaner 
clean 

150 

gram 

No.  1 

Std. 

dust  in 

h.p. 

with 

cleaner 

off. 
per  cent 

1 

Case 

96.0 

96.1 

95.2 

1-3/4 

1-11/16 

2.6 

27.0 

100.0 

2 

Cletrac  W 

89.3 

85.8 

83.6 

3-13/16 

5-1/8 

8.5 

26.6 

98.7 

3 

Dailey 

99.5 

99.9 

6-5/16 

22-7/16 

Run 

lost  due 

to  error 

4 

Dailey 

99.8 

99.9 

5-7/16 

18 

10.7 

26.6 

98.7 

5 

Donaldson 

97.8 

98.0 

3-1/8 

20-9/16 

4.5 

27.2 

100.6 

6 

Donaldson 

74.7 

67.4 

1-5/8 

2-7/16 

3.8- 

27.1 

100.3 

7 

Donaldson 

51.0 

50.3 

2-1/16 

2-5/16 

4.2 

27.1 

100.2 

8 

Donaldson 

96.5 

97.3 

95.0 

2-5/8 

4-3/4 

7.4 

27.0 

100.0 

9 

Fageol 

98.5 

99.5 

4-1/2 

16 

12.8 

25.7 

95.2 

10 

Fordson 

88.9 

89.8 

85.5 

7/8 

1-1/2 

3.3 

26.8 

99.3 

11 

I.H.C. 

94.6 

94.4 

92.3 

2-11/16 

2-7/8 

3.5 

27.4 

101.7 

12 

Palmer 

96.6 

96.9 

94.7  oil 

4 

6 

6.3 

26.9 

99.6 

13 

Success 

98.7 

97.8 

1-1/2 

27-1/4  + 

2.2 

27.0 

99.9 

14 

R.W. 

93.1 

92.6 

92.6 

3-1/4 

3-5/8 

8.3 

26.9 

99.7 

15 

Stewart- 
Warner 

95.7 

95.8 

Const,  level 

4-5/8 

5-9/16 

11.1 

26.5 

98.3 

16 

Taco  Siphon 

92.4 

94.0 

85.9 

2-1/2 

3-3/16 

5.8 

27.0 

99.8 

17 

Eiderdown 
(closed) 

99.4 

99.5 

2-5/16 

2-5/8 

5.6 

27.2 

100.7 

17' 

Eiderdown 
(open) 

Test 

not  run 

4.8 

27.0 

99.9 

18 

United 
(collector) 

73.3 

72.5 

9 

9 

12.7 

26.5 

98.2 

19 

United 
(ejector) 

62.2 

58.3 

3-3/16 

4-1/2 

9.3 

27.0 

99.8 

20 

Pomona 

98.4 

98.2 

2-3/16 

2-5/8 

7.2 

26.7 

98.8 

21 

Pomona 

98.8 

98.6 

2-5/16 

2-3/4 

5.3 

27.5 

102.0 

22 

Pomona 

97.4 

97.1 

1-5/8 

1-11/16 

4.8 

26.6 

98.3 

23 

Bennett 

42.7 

37.6 

5-1/2 

6-1/16 

8.9 

26.6 

98.2 

24 

Samson 

95.9 

95.2 

Not  run 

5-3/8 

5-3/8 

10.1 

27.0 

100.1 

24a 

Samson 

6.9 

26.8 

99.1 

25 

Stromberg 

88.5 

87.4 

4-3/8 

6-7/8 

11.1 

26.5 

98.3 

25a 

Stromberg 

8.8 

26.4 

97.6 

25b 

Stromberg 

7.0 

27.2 

100.6 

26 

Dailey 

99.7 

99.6 

8-1/8 

9 

17.4* 

26.7 

98.9 

27 

Bennett 

9.3 

26.8 

99.1 

♦Abnormal;  chaff  of  chaff  test  not  all  out. 


Bulletin  362] 


DUST   AND   THE    TRACTOR   ENGINE 


479 


TABLE  3 

Summary  of  ' '  Fill-up  Tests  ' ' 


Dust 

Water 

Clean- 

Test 

Lgth. 

B.H.P. 

Room 

Dust 

caught 

or  oil 

er  No. 

run 

run 

Temp. 

No.  2 

by 

going 

No. 

Min. 

°F 

Std. 
lbs. 

abso- 
lute 
cleaner 
lbs. 

over 
lbs. 

1 

114 

48 

20.4 

104 

9 

1/16 

0 

2 

102 

54 

20.4 

91 

5 

1/8 

.9* 

5 

71 

31 

20.4 

83 

50  gram 

1  gram 

0 

9 

22 
108 

20.4 
16 

78 
99.7 

0.16 
5 

t 
.05 

10 

28 

0 

13 

16 
68 

8 
36 

16 
20.4 

82 
67 

0.16 
3 

t 
.25 

15 

0 

16 

50 

38 

20.4 

85 

5 

.02 

0 

17 

138 
76 

23 

18 

20.4 
20.4 

92 
95 

5 
2.5 

t 
X 

20 

0 

21 

33 

30 

20.4 

76 

3 

1 

0 

22 

81 

36 

20.4 

100 

7 

1/8 

0 

24 

38 

56 

20.4 

86 

5 

1/8 

Trace 

26 

57 

62 

20.4 

76 

5 

t 

0 

Vacuum  due  to 

cleaner, 

inches  water 


Min. 


1-7/8 
5-1/8 
7-3/16 
6-3/8 
1-1/2 
11-1/4 
5-7/16 
2-3/4 
3 

2-3/4 
2-3/8 
1-3/8 
4-7/16 
8-5/8 


Max. 


11 
7 

20-9/16 

26-3/4 
2-5/16 

24-5/8 

16-1/8 
5-1/16 
4-17/32 
3-1/8 

14-5/16 
3-7/16 

26-3/8 

10 


Rate 
of  air 
flow 


53 
53 
55 

53 
47 
51 


55 
53 
54 
58 
55 


54 


Note 


1 

2 

3 

4 

5 

6 

7 

8 

9 

10 

11 

12 

13 

14 


Note    1. 

2. 
3. 


One  pound  sand,  etc.,  found  in  horizontal  inlet  tube  in  base  of  cleaner  at  close  of  test.   Dust 
of  previous  runs  (200  grams)  left  in. 

Cleaned  out  before  test. 


Dust  of  previous  runs  (100  grams)  left  in. 
dust. 


Not  deemed  necessary  to  use  any  No.  2  Standard 


4.  Dust  of  previous  runs  (100  grams)  left  in. 

5.  Dust  of  previous  runs  (200  grams)  left  in.    Tested  at  Fordson  load 

6.  Dust  of  previous  runs  (100  grams)  left  in. 

7.  Dust  of  previous  runs  (150  grams)  left  in. 

8.  Dust  of  previous  runs  (250  grams)  left  in. 

9.  Dust  of  previous  runs  (150  grams)  left  in. 

10.  Dust  of  previous  runs  (150  grams)  left  in 

pound  dust  in. 

11.  Dust  of  previous  runs  (200  grams)  left  in 

to  spray. 

12.  Dust  of  previous  runs  (150  grams)  left  in. 

13.  Cleaned  out  before  this  test. 

14.  Dust  of  previous  runs  (150  grams)  left  in. 

*  Amount  abnormal  since  rapid  rate  of  dust  feed  raised  water  level  about  5/8  inch  above  high  mark 

t  Not  weighable  on  1/4  oz.  sensitive  scale. 

%  Not  weighed. 

§  Cu.  ft./min.  60°F.  and  14.7  lbs./sq.  in. 


Dust  going  through  rather  freely  after  4th  half 
Sand  began  passing  to  trap  soon  after  oil  ceased 


480 


UNIVERSITY    OF    CALIFORNIA — EXPERIMENT    STATION 


TABLE  4 
Summary  of  Chaff  Tests 

(Ten  grams  dry  wheat  chaff  was  fed  to  cleaners  not  having  adequate  screen,  to  find 

effect  on  vacuum.) 


Cleaner  No 

Run  No 

Length  run,  Min 

B.H.P 

Rate  of  air  flow  cu.  ft. 
per  min.  60°F  and 
14.7  lbs./sq.  in 

Vacuum  due  to  Min. 
cleaner Max. 

Remarks 


1 

5 

8 

10 

17 

20 

24 

113 

72 

129 

107 

137 

77 

37 

10 

11 

30 

8 

8 

47 

33 

20.4 

20.4 

20.4 

16 

20.4 

20.4 

20.4 

53 

54 

53 

47 

53 

54 

55 

1-3/4 

3-5/16 

4-3/8 

1-1/8 

2-3/4 

2-11/16 

5-3/8 

1-3/4 

3-3/4 

10-3/16 

1-5/32 

2-7/8 

6-3/4 

32-15/16 

Note  1 

Note  2 

Note  3 

Note  4 

Note  5 

Note  6 

Note  7 

26 

58 

43 

20.4 


54 

9-5/8 
28-3/4 
Note  8 


Note  1.  Dust  (150  grams)  of  previous  runs  left  in. 

2.  Filter  cleaned  out  and  reoiled  before  test. 

3.  Drained  out  (but  not  flushed)  and  refilled  before  test. 

4.  Dust  (200  grams)  of  previous  runs  left  in.    Water  level  low. 

5.  Dust  (150  grams)  of  previous  runs  left  in. 

6.  Filter  cleaned  out  and  reoiled  before  this  test. 

7.  Dust  (150  grams)  of  previous  runs  left  in.   No.  24A  (received  too  late  for  test)  has  an  adequate 

screen. 

8.  Dust  (150  grams  No.  1  St'd.  and  5  lbs.  No.  2  St'd.)  from  previous  runs  left  in. 


NOTES  TAKEN  FROM  THE  TEST  RECORDS* 

Cleaners  nos.  3,  4,  and  26,  Dailey. — The  intake  cone  furnished 
regularly  with  this  cleaner  was  not  in  position  during  any  of  the 
tests.  Its  effect  would  be  to  increase  efficiency  and  vacuum  slightly 
and  to  lengthen  a  little  the  time  between  clean-outs. 

Cleaner  no.  4. — The  vacuum  measured  by  18  inches  water  (read 
after  150  grams  no.  1  standard  dust  had  been  fed  in)  dropped  to 
10%  inches  when  the  cleaner  was  jarred  with  wooden  mallet. 

Cleaner  no.  6,  Donaldson  Dry. — This  cleaner  is  designed  for  a 
larger  engine  than  the  25  h.p.  machine  used  in  the  tests.  After  the 
runs  on  this  cleaner,  a  large  quantity  of  dust  was  found  in  shroud 
of  cleaner.  The  efficiencies  found  were  therefore  higher  than  they 
would  be  after  runs  enough  to  fill  free  space  in  shroud. 

Cleaner  no.  8,  Donaldson  Water  Type. — This  cleaner  should  have 
a  more  obvious  place  for  filling  with  water. 

Cleaner  no.  12,  Palmer. — A  trace  of  oil  in  very  finely  divided 
form  was  found  on  top  cloth  of  absolute  cleaner  after  each  test.  When 
motor  idles  or  stops,  oil  settles  into  air  intake  tube  in  such  quantity 
as  to  cause  'choking'  of  carburetor.  This  vacuum  (fluctuating  about 
l!/4  inches  of  water)  might  cause  trouble  in  starting  a  warm  engine. 


4  See  also  notes  in  tables  of  summaries. 


Bulletin   362]  DUST  AND   THE   TRACTOR  ENGINE  481 

Cleaner  no.  15,  Stewart-Warner. — At  the  end  of  dust  feeding  in 
fill-up  test,  vacuum  due  to  cleaner  was  measured  by  161/g  inches  water. 
After  seven  minutes  longer  run  without  more  dust,  vacuum  decreased 
to  141%6  inches.  One  side  of  cleaner  was  almost  completely  clogged 
because  of  the  rapid  rate  of  feeding.  Some  iron  rust  was  found  in 
this  cleaner,  and  it  may  have  contributed,  to  the  clogging.  The  later 
cleaners  of  this  make  are  made  of  brass. 

Cleaner  no.  19,  United  Manufacturing  and  Distributing  Company 
Ejector. — A  test  of  length  of  life  of  the  bearing  was  run  on  this 
cleaner,  twenty-five  cubic  feet  per  minute  air  being  drawn  through 
by  vacuum  cleaner.  Time  216  hours  before  the  efficiency  tests,  315 
hours  after.  Total  531  hours.  Cleaner  chattered  a  good  deal  toward 
close  of  test. 

Cleaner  no.  23,  Bennett  Dry. — Run  (no.  64)  discarded  as  official 
service  run,  but  averaged  with  runs  62  and  63  since  dust  from 
previous  runs  (nos.  62  and  63)  probably  dropped  from  interior  walls 
of  cleaner  and  passed  on  to  absolute  cleaner.  If  cleaner  had  been 
shaken  during  and  at  close  of  runs  62  and  63  this  dust  would  have 
reduced  their  efficiencies.  Dust  (dry)  removed  from  cleaner  after 
runs  62,  63,  and  64,  totaled  61.90  grams. 

Cleaner  no.  25,  Stromberg  Ejector. — With  normal  load  and  speed 
and  with  cleaner  outlet  and  inlet  disconnected  from  other  apparatus 
and  closed,  expirator  produced  a  vacuum  inside  of  cleaner  body 
measured  by  12%  inches  water. 

Pressure  of  exhaust  gas  in  pipe  one  inch  from  cleaner  was  meas- 
ured by  11%  inches  water,  average,  during  first  tests  on  this  cleaner. 
During  the  last  tests  it  was  about  4%  inches.  The  difference  is  due 
probably  to  a  slight  change  in  the  point  of  exhaust  manifold  where 
gas  for  the  cleaner  was  piped  out.  It  is  interesting  to  note  that  the 
cleaning  efficiency  is  unchanged.  After  the  seven  runs,  a  carbon 
dej)Osit  about  %2  inch  thick  was  found  in  the  throat  of  the  expirator. 

Graphs. — Figure  6  shows  graphically  the  dust  separation  efficiency 
of  the  cleaners  tested,  and  makes  possible  comparison  individually 
and  by  groups.  Fig.  7  makes  possible  a  similar  comparison  with 
respect  to  the  choking  effect  and  how  this  changes  as  the  cleaner  takes 
in  more  and  more  dust.  It  will  be  observed  that  for  the  large 
majority  of  cleaners  the  vacuum  is  less  than  ten  inches  of  water  and 
either  constant  or  nearly  so,  while  for  a  few  it  runs  up  very  rapidly. 
Fig  8  shows  the  effect  of  each  of  the  several  cleaners  (when  clean) 
on  the  power  of  the  engine  and  the  effect  on  the  vacuum  when  the 
engine  is  giving  maximum  power.     The  curved  line  (used  in  each  of 


482 


UNIVERSITY    OF    CALIFORNIA EXPERIMENT    STATION 


the  four  parts  of  fig.  8)  was  obtained  by  measuring  the  maximum 
power  obtainable  from  the  engine,  first  with  the  carburetor  unob- 
structed, then  with  its  intake  closed  more  and  more  by  a  gate  valve. 
The  object  of  this  test  was  to  learn  whether  the  effects  on  power  of 
the  several  cleaners  were  due  only  to  the  vacuum  they  produced  or 
to  some  other  cause.  It  should  be  pointed  out  that,  while  the  utmost 
care  was  used  to  avoid  errors,  the  results  are  not  conclusive  for  the 
reason  that  the  effects  of  the  cleaners  (when  clean)  on  power  are  so 
small  that  it  is  possible  that  slight  changes  in  the  engine  itself  may 
in  some  cases  have  had  more  effect  than  the  presence  or  absence  of 
the  cleaner. 


Dust  SePAeAnno  frr/cic/icr.   Avc^agc  or  all  resrs.  pe/?cf/rr 

0  20  40  60  SO  100 


A 


v3 


7 

HI 

17 

—  iSXn 

i=i 

<N  /? 

lf\ 

Sc 

Y 

<9 

\U) 

n  ^ 

?$ 

P.I 

1 

I 

4 

m 

..  ....  ,„■,? 

j—, 

c^^ 

ii 

\w 

r~  ?_ 

i* 

i= 

u 

M 

16 

24 

4 

4 

s 

9 

IZ 

0 

:t 

no 

u= 

e,i 

^* 

26 

AV£KAOF 
ALL  TFSTS 
T47 


EmcieNcr     %■ 


•JSJL 


_8?_JL 


SL&. 


»f> 


924 


97S 


9SB 


sower 

6Z4 


Lot* 

fYATCR 


<5Q3 


978 


99S 


9*4 


seo 


H5£ 


.84  6- 


S>?6 


^SSZ 


OX.94, 


Fig.  6. — Graph  of  dust-separation  efficiency. 


Vacuum  effect  not  entirely  harmless. — While  it  has  been  shown 
that  none  of  the  cleaners  if  clean  has  very  much  effect  on  the  maxi- 
mum possible  power  of  the  engine,  it  must  not  be  assumed  that  the 
vacuum  effect  is  entirely  harmless,  especially  if  it  increases  as  dust 
is  absorbed  by  the  cleaner.  Tf  at  full  load  of  the  engine  the  vacuum 
be  above  about  10  inches  of  water  and  the  needle  valve  of  the  car- 
buretor be  set  for  correct  mixture,  it  will  be  found  (in  the  case  of 
some  carburetors)  that  at  half -load  the  lower  vacuum  and  hence  less 
suction  on  the  gasoline  jet  will  make  the  mixture  much  too  lean, 
possibly  causing  back-firing  and  even  stoppage  of.  the  engine.  If  it 
be  adjusted  correctly  for  light  load,  the  mixture  will  be  altogether 
too  rich  at  full  load.  Thus  the  high  vacuum  will  cause  one  or  the 
other  of  two  undesirable  conditions:  either  the  mixture  will  often 


Bulletin  362] 


DUST  AND   THE   TRACTOR   ENGINE 


483 


be  much  too  rich  (with  consequent  waste  of  fuel  and  rapid  carbon- 
ization of  spark  plugs  and  inner  walls  of  the  combustion  chambers), 
or  the  operator  will  be  under  the  necessity  of  adjusting  the  needle 
valve  too  frequently.  This  will  be  the  case  for  variable  load,  e.g.,  a 
tractor  on  drawbar  work.  For  belt  work  with  steady  load,  e.g.,  run- 
ning an  irrigation  pump,  a  vacuum  measured  by  10  inches  or  even 
15  inches  of  water  is  not  serious. 


CD 

-♦- 

O 
en 

(U 

n 
o 

c 


c 

D 

0) 

u 


3 
O 

5 


20 


X) 

o 
o 

o     ,5 

E 

u 
O 
Z. 


\Q 


7^"'         "^^Avff  n"d        d"r"y" 

/  _^   ^-—\  iX W  E  T.  I6^r-W£T      A  7  PR  V_ 


>HII  KWW 


rri ' 


-WET 


i 


-WET 


7^ DRV 


IOO 

I 


DRV 


/N2I- 


OIL 

oil 

££ OIL 


IpO       GPAM5 
OUNCES 


1 — I  l 1 1 — 

O  1  2  3  4  5 

Amount    No.  1    Standard  Dust    Fed  In. 

Note:     Sudden  increase    of    vacuum   was  due    to 

cloth  cone   inside    of  cleaner    being  sucked 

against  outlet    opening. 


Fig.  7. — Graph  of  vacuum  or  choking  effect.  A  line  rising  as  it  passes  from 
left  to  right  indicates  a  cleaner  the  vacuum  of  which  increases  as  dust  is 
absorbed. 


484  UNIVERSITY    OF    CALIFORNIA — EXPERIMENT    STATION 


HOW    TO     GET     BEST     RESULTS     FROM     AIR     CLEANERS 

No  leaky  connections. — No  leaky  connection  should  be  permitted 
between  air  cleaner  and  carburetor  or  between  parts  of  the  air  cleaner 
itself.  A  loosely  fitting  slip  joint  or  an  ordinary  flexible  metal  tube 
are  almost  sure  to  admit  some  air  and  a  great  deal  of  dust.  A  piece 
of  radiator  hose  fitting  tightly  over  the  tubes  to  be  connected  is  very 
satisfactory  if  the  connection  is  short.  If  long  and  the  vacuum  rather 
high,  the  hose  walls  may  be  caved  in  by  the  air  pressure  and  thus  the 
passage  be  obstructed.  In  such  a  case  the  line  may  be  spliced,  a  thin 
metal  tube  making  up  the  larger  portion  of  the  length.  Ordinary 
friction  tape  is  a  very  satisfactory  emergency  material  for  stopping 
air  leaks. 

Filters,  whether  of  cloth  or  fiber,  cannot  be  efficient  if  they  have 
holes  in  them.  The  dusty  air  will  go  in  largest  quantity  by  the  path 
of  least  resistance.    The  dust  will  find  the  hole  if  there  be  one. 

Breather  pipe  should  have  clean  air. — A  special  cleaner5  may  be 
used  or  connection  may  be  made  to  the  carburetor  air  cleaner.  If 
clean  air  is  not  provided,  the  breather  pipe  itself  acts  as  an  oil-type 
air  cleaner  taking  in  breaths  of  dusty  air,  collecting  the  dust  and 
sand  on  the  oily  walls,  then  blowing  out  puffs  of  clean  air.  When 
dust  goes  in  through  the  carburetor  there  is  a  chance  that  some  of  it 
may  escape  through  the  exhaust.  Not  so  with  dust  on  the  walls  of 
the  breather  pipe.  It  remains  until  the  oil  washes  it  down  into  the 
crank  case.  When  it  is  not  feasible  to  connect  the  breather  to  the 
air  cleaner,  a  small  bag  of  eiderdown  blanketing  or  cotton  flannel, 
lint  side  out,  may  be  tied  over  the  breather  pipe.  This  will  remove 
one  leading  cause  of  rapid  wear  of  timing  gears,  front  piston  and 
cylinder  and  front  main  bearing  in  some  tractors. 

Place  air  intake  high. — Except  in  orchard  work  it  is  usually 
possible  to  use  a  'periscope'  or  high  vertical  extension  for  the  air 
intake.  The  advantages  are  that  the  quantity  of  dust  to  be  removed 
by  the  air  cleaner  is  greatly  reduced  and  that  the  coarser  dust  is 
avoided.  Some  air  cleaners  are  regularly  furnished  with  a  jointed 
periscope.  Part  or  all  of  it  should  be  used  whenever  feasible.  If  a 
periscope  is  provided,  it  should  be  smooth  inside  and  free  from  sharp 
turns.  The  inside  diameter  should  be  amply  large  (not  less  and 
preferably  more  than  2  inches  for  a  10-20  tractor),  or  the  vacuum 
effect  will  be  unnecessarily  increased. 

s  The  market  affords  breather  air  cleaners  for  certain  tractors.     Manufacturers ' 
addresses  will  be  furnished  on  request. 


Bulletin  362] 


DUST   AND   THE   TRACTOR   ENGINE 


485 


Give  needed  attention. — There  is  not  on  the  market,  so  far  as  the 
writer  is  aware,  any  air  cleaner  that  can  be  put  on  a  tractor  or 
automobile  engine  and  forgotten  aftd  yet  month  after  month  give 
adequate  protection  against  dust.  All  require  some  attention  and  have 
their  own  peculiar  troubles.  Those  with  moving  parts  have  troubles 
due  to  wear  and  to  accumulation  of  dust  and  oil.  Thus  the  float  in 
some  water  type  cleaners  may  have  holes  worn  which  would  permit 
dusty  air  to  pass  without  going  through  the  water.     Centrifugal  types 


WET 


EFFECT  OF  AIR 
.EANERS  ON  POWER  OF 
MOTOR     I 


10 


20 


10        20  0  10         20  0  10         20  0 

VACUUM    AT    CARBURETOR     INTAKE. 

INCI-IE5    WATER      BELOW     ATMOSPHERE 


30'      40 


50 


Fig.  8. — Graph  of  effect  of  air  cleaners  on  power  of  engine.  The  curved  lines 
show  how  power  falls  off  as  carburetor  intake  is  choked  (no  air  cleaner  on). 
Distances  up  show  brake  horsepower,  distances  to  right  show  vacuum  or  choking 
effect  measured  in  inches  of  water.  Maximum  power  with  cleaner  off  was  27  h.p. 
Each  cleaner's  effect  on  power  and  vacuum  is  shown  by  position  of  the  numbered 
points. 


may  become  so  encrusted  with  oil  and  dust  that  their  action  may 
almost  entirely  cease.  Cleaners  having  small  passages  inside  may 
clog  up  solid.  Other  kinds  may  so  increase  their  vacuum  effect  due  to 
accumulation  of  dust  that  the  power  of  the  engine  may  be  greatly 
reduced.  Nearly  every  air  cleaner  has  its  plate  giving  the  manu- 
facturer's directions  for  the  care  required.  Some  tractor  operators 
may  be  able  to  improve  upon  these  directions,  but  none  may  safely 
neglect  them. 


486  UNIVERSITY    OF    CALIFORNIA EXPERIMENT    STATION 


A    SIMPLE    EFFICIENCY   TEST    FOR    AIR    CLEANERS 

Not  what  the  air  cleaner  catches,  but  what  it  lets  go  by  does  the 
mischief  in  a  tractor  engine.  Whether  any  appreciable  amount  of 
dust  gets  past  an  air  cleaner  may  usually  be  known  by  disconnecting 
the  air  cleaner  from  the  carburetor  and  wiping  out  the  inside  of  the 
connecting  tube.  If  after  a  ten-hour  run  under  dusty  conditions  only 
a  trace  of  dust  can  be  wiped  out,  the  cleaner  has  probably  done  a 
first-rate  job.  This  test  may  fail,  if,  as  might  possibly  happen,  so 
much  water  or  oil  should  go  over  from  the  cleaner  that  the  tube  would 
be  kept  washed  out. 

ACKNOWLEDGMENTS 

The  author  wishes  to  acknowledge  his  indebtedness  to  manufac- 
turers who  loaned  apparatus  and  made  helpful  suggestions  as  to  test 
methods,  to  members  of  other  divisions  of  the  University  of  California 
for  equipment  placed  at  our  service,  to  Professors  Fletcher,  Thomson, 
Moses  and  others,  who  furnished  counsel  and  active  assistance  in  the 
testing  work. 


